Apparatus for coating fluorescent lamp tubes



Nov.v25, 1947. K. DEMB Erm.

APPARATUS FOR COATING FLUORESGENT LAMP TUBES IN1/mrow. Kcmuvu ogn;

Filed Dec. 27, 1943 Patented Nov. 25, 1947 APPARATUS FOR COATING LALIP TUBES FLUORESCENT Kenneth Demb, Salem, and Malcolm L. Hayes, Beverly, Mass., assignors to Sylvania Electric Products Inc., Salem, Mass., a corporation of Massachusetts 'Application December 27, 1943, Serial No. 515,858

10mm. l

This invention relates to coating of elongated tubes on their interior surfaces, and particularly to coating the interior surfaces of glass lamp tubes with fluorescent materials.

An object of the invention is the provision of simple and effective means for coating the interior of elongated electric lamp tubes with fluorescent material.

`A further feature of the invention is an apparatus for coating such a tube in which a spray nozzle moves through said bulb in an accurately aligned path to perform the spray.

Other'features and advantages of the invention will be apparent from the following specification taken in connection with the accompanying drawings, in which:

Figure 1 represents a side view of the apparatus according to our invention;

Figure 2 is a view, chiefly in section, of the input end of the spraying nozzle;

Figure 3 is a view partly in section of the output end of the spraying nozzle;

Figure 4 is a view of the apparatus for start ing and stopping the automatic retracting of the spraying nozzle from the tube being coated.

In Figure 1 the lamp bulb I is held rigidly in place by the supports 2 and 3 at each end of the bulb. Support 3 also serves to close of! the corresponding end of the bulb. The spring 4 presses support 3 against the end of the tube I Inside the spring 4 is the rod 5 attached to the support and mounted in the bearings 5, in which it may rotate. The pulley 1 is fixed to rod or shaft 5 and may be rotated by a belt running from a motor. The rotation of the pulley 1 is transmitted to the bulb I, through the rod 5 and support 3. A reduction gear may be used to reduce the speed.

The spray gun 9 is supported at its forward end by the roller I attached to support I I, while the rear or input end of said spray gun 9 is ixed by nut I to the carriage I2 movable along track I3 by means of wheels I4.

The carriage I2 is connected to chain I5 by means of clutch I1, (including its stop 52), sov

that the nozzle 8 can be inserted by hand through support 2 into tube I to `a position near. but spaced slightly from the support 3, and will then be retracted automatically at constant speed'by the chain I6 to the position shown in the figure.

The path of retraction of the nozzle 8 must be accurately aligned with the position in which bulb I is held by supports 2 and 3, to give a uniform spray coating. Instead of moving the spray gun, the gun may be fixed and the bulb moved 2 with respect to it to give the same relative motion. The chain I5 is operated by the sprockets I8, one of which is driven from electric motor I9 throughreduction gears 20. 'Ihe heavy metal 5 frame pieces 22 support the apparatus, assisted by legs 23, 24 and 25, uprights 25 and 21, and Pieces 28 and 29. l

Air under pressure flows into the spray gun 9 at inlets 30 and 3|. The coating solution flows into inlet 32 from container 33 which would ordinarily be mounted higher than indicated in the drawing to secure proper now.

Figures 2 and 3 show the nozzle 8 and its associated parts in more detail. The coating solution flows into inlet 32 and thence through pipe 34 into the internal liquid carrying tube 35, and out through opening 36 at the end thereof. The needle 31 normally closes said opening, and ex.- tends through bushing 38 and plate 39 to termil nate in piston 41, backed by packing 4I, plate 42, spring 43, and end piece 44 and its cap 63.

Air flows into inlet 3| and around the internal liquid carrying tube 35 and out through opening 45 in nozzle 8 to mix with, and carry forward with it, the coating solution in the form of spray. Inlet admits air to chamber to drive piston 41 back against the pressure of spring 43. to 'withdraw needle 31 to allow solution to flow out opening 38.

Figure 4 shows an attachment to carriage I2, which may be used to start and stop the driving motor I9. A ring 64 is supported from carriage I2 by piece 65. Rod 48 is set inside ring 64 and parallel -to the direction of motion of carriage I2. The rod 48 moves through fixed ring supports 49 and 58 (which may be supported from the frame piece 22 of Figure 1). One end 5I of rod 48 is attached to an end 52 of lever 53, which is attached to support 54 as a fulcrum. The other end of lever 53 is attached to a conventional mercury switch 55, from which extend wires 56 and 51 to the control circuit of motor I9.

When the carriage I2 moves forward ring 64 pushes against ring 58, xed to rod 48 by set screw 59. This raises mercury switch 55 and closes it. starting motor I9. When the carriage is retracted to the end of itsy journey, ring 84, bears against ring 60, fixed to rod 48 by setscrew 5I, and pushes the switch 55 back to its open position, shutting off the motor I9. 'I'he rod must be balanced properly, or enough friction provided to keep it in either position to which it isy pushed. i

The same mercury switch control mechanism 55 can be used also to open valves admitting air to 3 inlets ll and ll, and coating solution to inlet 32 when the motor I! is started. and to close said valves when-the motor is stopped, in a conventional manner. 1

We have used an atoxnizing air pressure of 70 lbs. per souareinch, and' a coating solution level of4 72 inches above vthe vnozzle 9. If desired, a

form of spray not requiring atomizing air pres- "surecanbeused.

:Although for clearness in Fig. 1. the chain I8 with itssprockets I8 is yshown at the side of frame 22 and carriage I2, we prefer to place it directly below thecarriage ,12. so that there will be less tendencyto sidewise motion of carriage lI! while being retracted. The carriage I2 and chain Il should be quite'heavy'to iurther' insure a Vsmooth motion of the spray nozzle l through the Vtube l. .Any-irregularity in this motion will .be dry produce unevenness in the coating.'

ber 30,' 1941 to R, M. Gardner. v

In some casesthe holder 3 may have a hole through-,which suction or air pressure lines 'y can be connected to .the endoi' the tube. In this Yway the spray nearthe end of the tube can be i forced back from,for brought toward. the end of the tube'li being coated to 'control the thickness vwhatwe511111111111.- t'

Apparatus for a suspension oi' lumi# `4neseentf mateiiel: tofthezinner wa1l'of:an e1on- ,gated glass envelope, said' apparatuscomprising:

at of the bulbto a l 4 a base member', a pair of supporting members mounted on said base member for 'embracing the ends oi' said envelope, one of said supporting' members being provided with an aperture therein, a track mounted on said base member, a carriage on said track, aspray gun 'mounted'on said carriage, said -spray gun comprising an .elon

gated barrel and a'nozzle'mounted on one end of said barrel, said nozzle having an aperture therein, means for supplying air under pressure to said nozzle, means for supplying Aa -suspension of luminescent material to the aperture in said nozzle, means forl controlling the opening and closing of the aperture in said nozzle whereby the flow o! luminescent material suspension therefrom may be regulated, and means for moving' forward and retracting said carriage along'said track and said nozzle through the aperture'in one of said supporting members and'v toward theother of `said supporting members,

- whereby a coating -of lluminescent material mayl Y 2,1813305 4 Myers Nov. 28, 19394 35 .2,275,437 Hopkins 1 Mar. 1o, 1942 2,314,515 1 Parson Mar. 23, 1943 Y 2,336,946 Marden 'et al. Dec. 414, 1943 2,344,081 Claude ..l Maig-14, 1944 2,344,905 Short .f Mar, 21,1944

,of supporting members.

` be applied to the inner wall of an elongated glass envelope. the ends' ofwhich are held by said pair KENNETH DEMB. y

lMALCOLM n I AYEs.

,Y annu caserma Thef following references. are of' record ,in the .ille of 2' UNITED srA'rEs PATENTS 

